The Dorper is a hardy South African composite breed, derived from a cross between the Black-headed Persian and the Dorset Horn. Dorpers are regarded as early-maturing, and ewes lambed at an age of 1 year in one study. Age at first lambing was higher in other literature sources cited. The fertility of Dorper ewes was approximately 0.90 ewes that lambed per ewe mated, with a litter size ranging f...

The IgG1 concentrations in two-day-old lambs were significantly correlated with litter size, date of lambing, length of gestation and age of the dam. When these and other effects were allowed for significant breed differences were found, the concentrations being relatively high in Finnish Landrace, Welsh Mountain and Soay lambs, and relatively low in Border Leicester, Oxford Down and Southdown ...

The water vole (Arvicola amphibius) in the forest-steppe of West Siberia is known to have wide fluctuations in abundance. These fluctuations are accompanied by changes in birth and death rates, sex-age structure of the population, and individual morphophysiological and behavioral characteristics of the animals. Survival of the animals depends on season, phase of population cycle, and sex. Based...

Historically, Rocky Mountain National Park (RMNP) has supported a small black bear (Ursus americanus) population of low productivity. Increased visitor use of the park and development around its periphery could lead to a reduction in population viability of RMNP’s bear population or could increase the potential for human–bear conflict. Therefore, we investigated contemporary survival and produc...

Genetic factors affecting female reproductive performance in lines of mice with a known history of selection were estimated from a 5 X 5 diallel cross. Lines were selected as follows: large litter size at birth (L+); large 6-wk body weight (W+); an index for large litter size and small 6-wk body weight (L+W-); the complementary index (L-W+) and randomly (K). Partitioning of direct and correlate...

Laboratory crosses between wild strains of the two European house mouse subspecies Mus musculus domesticus (2n = 34) and M. m. musculus (2n = 40) were performed to analyze the selective processes involved in the non-introgression of centromeric regions of Robertsonian (Rb) fusions in the Danish hybrid zone. The chromosomal analysis of 226 backcross progeny from 22 reciprocal crosses showed that...

Data from 364 ewes of Sardi (S), D'man (D), S x DS, DS x S, S x D, D x S (F1), F2, D x DS and DS x D breed groups mated to F1 rams were analyzed for fertility, number of lambs born alive, litter size at weaning, litter weight at weaning per ewe joined and mean lamb weight at 60 d. Each ewe was exposed in two seasons and had one or two lambings. Effects of breed group were significant for all tr...

Anthropogenic degradation of the world's ecosystems is leading to a widespread and accelerating loss of biodiversity. However, not all species respond equally to existing threats, raising the question: what makes a species more vulnerable to extinction? We propose that higher intraspecific variability may reduce the risk of extinction, as different individuals and populations within a species m...

The objective of this study was to carry out a sensitivity analysis on the impact of various production strategies and performance levels on the relative economic values (REVs) of traits in dairy sheep. A bio-economic model implemented in the program package ECOWEIGHT was used to simulate the profit function for a semi-extensive production system with the Slovak multi-purpose breed Improved Val...

In this study, a novel 'rope-assisted swab method' for the collection of saliva samples from 45 adult pigs was established and validated. This method was efficient for harvesting 2 milliliters or more of saliva from each of the pigs for subsequent analyses within two min. The amount of α-amylase and lipase in the collected saliva samples was between 38-6,655 and 2-52 U/l, respectively. For HCO3...